Search for "The Great Vowel Shift" and "predictable phonological change".
I was reading one of those semi-news blogrolls a while back and there was a blurb about a research group that had produced a paper backed by a piece of software that can age a spoken language with fairly high accuracy. As always, I take such claims with a truckload of salt.
It's amusing how many glyphs have outright disappeared in the last few hundred years, like thorn and long s. The long s is particularly interesting because it was still in popular use at the founding of the United States and was used in the Declaration of Independence and Constitution (meaning that what you read of these documents in text reprints these days is literally not what the framers wrote).
http://xkcd.com/1012/